The invention relates to controlling the temperature of an article during treatment in vacuum.
Certain treatment processes must be carried out in a vacuum environment, e.g. treatment by ion or other particle beams in which the particles would be hindered by presence of gas molecules, etc. in the beam path.
Heat transfer between surfaces in a vacuum occurs primarily by radiation. This is true even of surfaces that appear to be in contact, because, in actual fact, due to surface irregularities, only point to point contact occurs, even between mirror polished surfaces. Without gas molecules to bridge the gaps between actual points of contact, heat transfer by other means, e.g. by conduction, generally cannot occur. In a number of processes, heat transfer by radiation is not sufficient, e.g. in high energy beam systems, heat conduction from the article is necessary to avoid damage to the article. In other processes, a certain minimum article temperature is required prior to treatment.
Means have been proposed in the prior art for improving the conductivity in a vacuum between the article to be treated and an adjacent temperature control surface. These means have included: vacuum grease, deformable plastic, and an interfacial gas layer, among others, but none are suited to many situations, e.g., due to the nature of the article to be treated.